Deaeration apparatus



Filed Jan. 23. 1946 1951 H. VON KOHORN ET AL 2,570,171

DEAERATION APPARATUS 2 Sheets-Sheet l """J. l A

ATTORN E Y5 1 5 H. VON KOHORN ET AL 2,570,171

DEAERATION APPARATUS Filed Jan. 23, 1946 2 Sheets-Sheet 2.

INVENTORJ 2 M ATTORNEYS Patented Oct. 2, 1951 DEAERATION APPARATUS HenryVon Kohorn and Ralph S. Von Kohorn, New York, N. Y.

Application January-23, 1946, Serial No. 642,991

2 Claims. 1

Our invention pertains. to a methodand apparatus for the continuousmanufacture .of rayon, staple ,fiber, transparent'cellulose sheeting,and other cellulose derivatives, by .the viscose method. Our inventioneliminates the batch method commonly employed in the manufacture ofviscose, and results in a saving of time,aspace, labor, and investment.

.According to our. invention, we place purified cellulose, such aswoodqpulp of rayon grade, or bleached cotton linters, on. an endlessconveyor belt, or other conveying means. While onsuch conveying means,the cellulosicraw material is first subjected to thenormalsteepingprocess or mercerizing, as practised by persons skilled inthelart. 'We then subject thealkali cellulose thus formed topressure,.suchas between squeeze rollers, .in order to extract excesscaustic soda solution, alkali cellulose of known nature resulting fromsaid extracting action. We then subject the alkali celluloseto ashredding or disintegrating action, either by passing it through acontinuous shredder, or by chopping it while traveling on an endlessbelt or conveyor.

After such shredding, disintegrating or chopping :action, we heat thealkali cellulose while continuously traveling on conveyor means,thereafter cooling the alkali cellulose toea' point where the alkalicellulose, thus aged, is readyfor sulfidizing with carbon bisulfide.This method :of ageingfknownras short-ageing, has been described in U.S. Patent No. 2,218,836.

-As an alternative, we first mercerize, then heat, then-extract, in theorder set forth, leaving the order of the other steps unchanged, exceptthat the cooling may take place before or'after the extracting step.This alternative has the additional advantage of permittingdissolvedhemiand oxycel luloses, contained or created in the heatedalkali cellulose, to be extracted bypressure together with the excesscaustic soda solution, thus reducing undesirable components of the:alkali cellulose.

When describing thepreferred sequences of operations according to ourprocess, we do not wish to be limited to the precisely defined timecycles. Certain herein described steps particularly the heating .and tosome extent the cooling step, may overlap the time cycle of other stepsor take place concurrently with them. Thus, for example, heating maystart during mercerizing, even though the mercerizing step itself mayjust be commencing or may not yet be completed. Cooling may commenceduring extraction .or shredding, and mayoverlap the first stage of thesulfidizing step. We select theuexact order of steps in'accordance withthe nature :of-thecellulose material used, and the properties of the viscose desired, provided always, however, .thatxthe alkali cellulose, ifheated, must be cooled sufiiciently and in time toavoid danger-of-ex-plosion during the sulfidizing step, and prior-to dissolv Whilethe alkali cellulose :is ,still' travelingqon the continuous conveyingmeans, we treat the same with carbon bisulfide, and we preferably carryout this step Whilethe-endless-conveying meansareienclosed in a housingin order towprevent carbon bisulfide fumes from escaping. At the sametime, we gent-1y agitate or vibrate the endless convey-ing means inorderto, assure completeand thorough actionof the-carbon bisulfide' on thealkali cellulose-forming xanthate, .as now practisedby persons skilledin the art.

We thereafter continuously feed the :xant-hate into .aamixing tank,feeding at the same time caustic sodasolution to. result in viscose ofnormal consistency and analysis, as practised by :persons skilled in theart.

Gur mixing or dissolving tank is-constructed :in such-a way as to feedxanthate and caustic .soda solution at one end, and to discharge theviscose at the :other end, in continuous fashion.

The viscose obtained in continuous manner :as described above, is thenpumped or forcedby compressed air, and, still in continuous: manner,intorand througha series of pipes or other tanks in ordentogive theviscose an opportunity tov ripen tothe desired degree, dependingron thetype of product. desired. :Intermittentlmpr :at one stage of thisoperation, the viscose .is forced through. a filter-medium-in order to.remove, still in :a continuous mannenany undissolved particles containedin theviscose. After" the desired degreeoffiltration .andripening hasbeen obtained, the viscose is fedintoa vessel which is subjected to :apartial vacuum. 'While slowly and .in continuous manner, passing through.this vessel, or large pipes, the viscose is thus deaerated and isnowready for the spinning, castingv or. other. coagulationandprecipitating steps.

.Our method of continuously de=aerating.vis cosepermits, the viscose tobe subjected'to a partial vacuum in suchiaumanner as to present thelargest possible surface :and the least depth through which'air or gasmust'rise through 'the viscose inorderrtoibe' absorbed by the vacuum.According to -our method,..the viscose. isrpermitted to -spread'outzhorizontallyi in. suitably. designed vessels :orr;pipes,1thuspresenting .eai .large, horn zontal, aggregate surface area to thepartial vacuum, and at the same time, reducing the vertical depth orlayer of viscose at each particular point. We achieve this by feedingthe viscose into a tank equipped with a series of inclined splash orbaffie boards, along which the viscose is permitted to flow in a thinlayer, said splash or baflie boards being of suitable length, width, andinclination. After deaeration, we collect the viscose again in suitablepipes of usual diameter.

In the drawings, Figure 1 illustrates one embodiment of the vessel usedfor this purpose. Figure 2 shows a series of pipes through which thetapering exit from the intermediate zone 23a and being of decreasingcross-section from the intermediate zone 23a to the outlet manifold 26.The manifold 22 is provided with an inlet pipe 2| whereas the outletmanifold 26 is connected by way of suitable piping to the inlet of agear pump 21 driven by a motor 28. The output of the pump 21 dischargesthrough a pipe 29. Furthermore each of the conduits 23 is connected byway of vacuum lines to a suitable vacuum pump which is driven by a motor32.

In operation a liquid to be de-aerated such as viscose is fed to theinlet manifold 22 through the pipe 2| and is there distributed to theconduits 23. In passing through the inlet end zones 2312 the fluidspreads into a relatively shallow stream and as such flows by gravitydownwardly through The viscose is fed into the tank shown in Figure 7 1,or into the pipes shown in Figure 2, at the top, either by gravity, orby means of pumps. It is removed frorrithe tank or the pipes at thebottom, by means of gravity or pumps, and from there transported intointermediary vesels, through additional filters, or to the extrudingmechanism.

Figure 1 shows a side elevation and Figure 1A shows a plan view of anapparatus for the continuous deaeration of viscose and other solutions,comprising a closed housing I, the crosssection of said housing being amultiple of the cross-section of the feed pipe 2 for the solution. Thesolution enters the apparatus through feed pipe 2, inlet header 3, andis distributed by inlet pipes 4. The viscose passes over interiordeflecting members 5, having a large aggregate surface and an inclinedposition so as to permit the solution 6 flowing by gravity and in acontrolled path from the top to the bottom of said housing I, to spreadout over a large area. The direction of flow is indicated by the arows"I. Vacuum pipe connections M are mounted on housing I, permitting theexposure of all of said interior members and of the solution toless-than-atmospheric pressure. Outlet pipes 8, outlet header 9, gearpump l0 (driven by motor I I), and outlet pipe I 2, represent means fordischarging, collecting and removingsaid solution from the lower part ofthe housing. Vacuum lines M, are connected to vacuum pump l3, driven bymotor l5. Deflecting members 5 are mounted in such a way that the lowerend of each sheet 5 closely approaches the sheet underneath in order toprevent the liquid from dripping over a considerable height so as toprevent the formation of air bubbles.

Referring now to Figures 2 and 2a of the drawings which illustrateanother embodiment of the present invention and wherein Figure 2 is aside elevational view thereof and Figure 2a is a top plan viewthereisprovided a horizontal inlet manifold 22 and a horizontal outlet manifold26 which is parallel to and spaced laterally from and below the inletmanifold 22. A plurality of inclined tubular conduits 23 of circularcross-section connect and provide communication between the manifolds 22and 26 and include a major intermediate zone 23a of substantiallyconstant cross- .section and coaxially aligned inlet and outlet endzones 23b and 23c respectively. The end zone 23b provides'communicationbetween the inlet manifold 22 and the intermediate zone 23a and alsoprovides an outwardly tapering entrance to the intermediate Zone 2311 ofincreasing cross-section from the manifold 22 to the intermediate zone23a; Similarly the end zone 230 provides communication between theoutlet manifold 26 and the intermediate zone 23a providing an inwardlythe intermediate zone 23a in the direction of the arrow 25. The fluidthen flows through the end zones 230 into the manifold 26 from where itis removed by the pump 21. The fluid in its passage along to conduits 23is subjected to sub-atmospheric pressure where de-aeration occurs. Thisde-aeration is accelerated as a result of the small depth of the fluidstream as it flows along the conduits 23. a

When using an intermediary tank, we place the same under pressure,regulating the level of the viscose in said tank, so as to leave anempty space at the top of the tank. The viscose is forced into said tankby means of a pump or other means, which exert sufficiently strongpressure to force the viscose into the above-described pressure-chamber,thereby overcoming the pressure prevailing in it. Thepressure chamber ortank has an outlet at the bottom, and the viscose in the tank is forcedthrough said outlet. Thus, while viscose is continuously fed into thepressure chamber against the pressure prevailing in it, viscose is alsocontinuously and simultaneously forced out of the pressure chamber bythese same pressures. In addition to the pressure de scribed above, theviscose can also be transported by pumps from this vessel in continuousmanner into the spinnerettes, casting device, or other extrudingmechanism which delivers the viscose into a setting bath, as practisedby persons skilled in the art of making rayon, staple fiber, transparentcellulose sheeting, or other cellulose derivatives of the viscose type.

Whereas the chemical'operations as such are the same as those nowpractised in the viscose products industry, our method of continuouslyperforming said known operations without the use of batches at anystage, is new.

We have explained the principle and mode of operation of our inventionand have described embodiments thereof. However, we desire it understoodthat, within the scope of the appended claims, the invention may bepractised otherwise than as specifically illustrated and described.

What we claim is:

1. Apparatus for the de-aerationof viscose or the like, comprising apair of manifolds relatively disposed in vertically and horizontallyoffset positions, a plurality of tubular conduits connecting saidmanifolds with each conduit sloping downwardly and each having a majorintermediate zone of constant cross-section and end zones connecting theintermediate zone with the respective manifolds, each end zone being ofrelatively short length and axially alined with the intermediate zoneaxis, the cross-sectional area of each end zone decreasing in thedirection I of the manifold to which it is connected to there by form atapering entrance and exit for the in termediate zone, whereby theentering material for the intermediate zone is spread by the enteringtapered zone to provide a content of relatively small depth to therebytraverse the major zone under substantially uniform cross section streamform with the depth of the stream determined by the tapered exit zoneleading to the lower manifold, each conduit having a substantiallygreater transverse cross-sectional area than a similar area of the uppermanifold, and means for producing a sub-atmospheric pressure in saidconduits.

2. Apparatus as in claim 1 characterized in that each conduit crosssectionally is of circular contour to thereby present a cross section ofthe content of the intermediate zone as having the contour of thesegment of a circle.

HENRY VON KOHORN. RALPH S. VON KOHORN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,357,947 Borzykowski Nov. 9,1920 1,877,337 Kampf et a1 Sept. 13, 1932 1,895,192 Kampf Jan. 24, 19332,005,811 Steimmig June 25, 1935 2,020,250 Stephens Nov. 5, 19352,087,016 Bradshaw et a1 July 13, 1937 2,146,532 Crane et a1 Feb. 7,1939 2,355,057 Copeland Aug. 8, 1944 FOREIGN PATENTS Number Country Date700,710 France Jan. 2, 1931

